Esteria is the setting of Ys I: Ancient Ys Vanished. It is a small island where people make their living by fishing. Once the mythical Kingdom of Ys stood here but only traces of it now remain in forms of the huge crater, Darm Tower, and the Shrine. Despite its proximity to the Romun Empire, it hardly received any attention.
However, everything changed when someone found the strange ore called cleria at the mine of Rasteenie. Due to its strong durability and magical power, cleria ores mined were sold at high prices. Many merchants and miners from outside word flocked to Esteria and Esteria enjoyed unprecedented prosperity.
Despite the increasing demand for cleria, the descendants of the Fact family strongly opposed the further mining for they knew cleria was one of the causes of the fall of the kingdom of Ys 700 years ago. Unfortunately, they were brutally murdered by the angry mob and their son Dark Fact, after witnessing the murder, disappeared without a trace.
Eventually, unchecked mining of cleria eventually caused the seal on demons to be broken. Esteria became infested with monsters while storms appeared in the sea, cutting off any contact from the outside world. Soon, the rumor spread across the outside world that Esteria is cursed and no one dared to go to the island.
Around this time, an adventurer by the name of Adol Christin arrives at Promalock harbor near Esteria. Hearing of the rumors, he embarks on the reckless challenge to go through the sea of storm surrounding the island and investigate the disasters that have fallen on Esteria, which would lead to his uncovering secrets behind the ancient kingdom of Ys and its mysterious disappearance 700 years ago.